/*
 * Copyright (C) 2001-2017 Jacek Sieka, arnetheduck on gmail point com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "stdinc.h"
#include <cmath>

#include "HashBloom.h"
#include "MerkleTree.h"

size_t HashBloom::get_k(size_t n, size_t h)
{
	for (size_t k = TTHValue::BITS / h; k > 1; --k)
	{
		uint64_t m = get_m(n, k);
		if (m >> 24 == 0)
		{
			return k;
		}
	}
	return 1;
}

uint64_t HashBloom::get_m(size_t n, size_t k)
{
	const uint64_t m = (static_cast<uint64_t>(ceil(static_cast<double>(n) * static_cast<double>(k) / log(2.)))); // [!] PVS V113 Implicit type conversion from memsize to double type or vice versa. hashbloom.cpp 23
	// 64-bit boundary as per spec
	return ((m + 63ULL) / 64ULL) * 64ULL;
}

void HashBloom::add(const TTHValue& tth)
{
	for (size_t i = 0; i < k; ++i)
	{
		bloom[pos(tth, i)] = true;
	}
}

bool HashBloom::match(const TTHValue& tth) const
{
	if (bloom.empty())
	{
		return false;
	}
	for (size_t i = 0; i < k; ++i)
	{
		if (!bloom[pos(tth, i)])
		{
			return false;
		}
	}
	return true;
}

void HashBloom::push_back(bool v)
{
	bloom.push_back(v);
}

void HashBloom::reset(size_t k_, size_t m, size_t h_)
{
	bloom.resize(m);
	k = k_;
	h = h_;
}

size_t HashBloom::pos(const TTHValue& tth, size_t n) const
{
	if ((n + 1)*h > TTHValue::BITS)
	{
		return 0;
	}
	
	uint64_t x = 0;
	
	size_t start = n * h;
	for (size_t i = 0; i < h; ++i)
	{
		size_t bit = start + i;
		size_t byte = bit / 8;
		size_t pos = bit % 8;
		
		if (tth.data[byte] & (1 << pos))
		{
			x |= (1i64 << i);
		}
	}
	return x % bloom.size();
}

void HashBloom::copy_to(ByteVector& v) const
{
	v.resize(bloom.size() / 8);
	for (size_t i = 0; i < bloom.size(); ++i)
	{
		v[i / 8] |= bloom[i] << (i % 8);
	}
}
